1. Field of the Invention
The present invention relates to electrical probes and, more particularly, is directed toward electrical planar probes employed as cooperative terminations and terminations for transmission lines.
2. Description of the Prior Art
In many test applications, it is necessary to provide for the temporary termination of electrical signal transmission lines to units under test. Often, spring-loaded, single-contact probes are employed for such termination. Arranging the single-contact probe or some other device for the efficient termination of coaxial signal transmission lines has been a long-standing goal. Currently available devices suffer from certain disadvantages and limitations because they do not provide high coaxial termination efficiency. Additionally, spring-loaded devices tend to compromise the transmission efficiency of some coaxial transmission lines since the signal at the transition of the spring device may not encounter a transparent boundary. Further, a test apparatus often requires additional interfaces in the signal transmission path due to other design or manufacturing considerations. Multiple interfaces degrade the performance characteristics due to their collective inefficiency.
In the current and future manufacturing test process of high speed devices, where a large number of test interfaces must be made at once, a need exists for a termination technology barrier that does not suffer from the foregoing disadvantages and limitations.
It is an object of the present invention to provide a planar probe device that does not suffer from the limitations and disadvantages of prior art devices.
It is a further object of the invention to provide a pneumatic planar probe device which allows planar termination to a receiving structure.
It is yet another object of the present invention to provide a pneumatic planar probe device that establishes and maintains electrical characteristics for the purpose of impedance characteristics matching of the probe.
It is still a further object of the invention to provide planar termination of an electrical transmission line between two cooperative receiving structures, an intermediate interconnecting interface or an interface array.
It is still another object of the invention to provide planar termination of an electrical transmission line to a transmission line receiving structure, a connecting singular interface or an interface array.
It is yet another object of the invention to provide means for selectively activating and deactivating a planar termination on command.
It is a further object of the invention to provide a compensated impedance transition between an electrical transmission line and a transmission line receiving structure.
It is still a further object of the invention to ensure compensated impedance transition between the electrical transmission line and the transmission line receiving structure when signal transmission occurs.
It is also an object of the invention to provide design latitude for the user so that operational forces can be adjusted for impedance transition.
It is also another object of the invention to provide a user adjustable planar probe termination configuration for matching transmission line receiving structure requirements.
It is also a further object of the invention to maximize the design freedom afforded to receiving structures.
It is still a further object of the invention to simplify the manufacture of a planar probe by utilizing simple bodies of revolution and standard assembly techniques.
It is yet another object of this invention to provide increased density in an array of planar probes.
It is another object of the invention to provide a pneumatic planar probe that can be easily inserted and removed from a header.
Other general and specific objects of the invention will in part be obvious and will in part appear hereinafter.
The pneumatic planar probe embodying the invention for electrical transmission lines includes a single contact or multiple contacts that are arranged to permit planar termination to a receiving structure. The probe also establishes and maintains electrical characteristics for the purpose of impedance characteristics matching of the probe. Termination of electrical transmission lines through the probe is complemented with impedance compensation, whereby the probe is transitioned to both the transmission line impedance and the receiving structure impedance. Single or multiple probes can be arranged to mate a receiving structure. Operation of the probe results in an established termination configuration which is reliable and repeatable. Further, the probe can be operated so that a range of contact forces is afforded to the user and the probe can be tailored to individual applications. There are no springs or biasing requirements for the probe. When the probe is not in operation, there are no residual forces involved.
The invention addresses termination technology barrier problems and enhances the practicality of current and future manufacturing test procedures for high speed devices.
The pneumatic planar probe embodying the invention includes a first probe body and a second probe body that are arranged as an extension of a transmission line having a center conductor and an outer conductor. The pneumatic planar probe is received in a header that is configured to be attached to a receiving structure. The first probe body and second probe body extend the transmission line""s outer conductor and center conductor, respectively. Support for the second probe body is provided by a dielectric body. The second probe body and the dielectric body are slidably mounted in the first probe body. The first and second probe bodies can be positioned relative to each other such that a first interface of the first probe body and a second interface of the second probe body can achieve any planar position requirement of a receiving structure. A plurality of contact fingers is provided for maintaining electrical continuity with the center conductor regardless of the incremental position of the second probe body relative to the first probe body. A first annular volume is pressurized to urge the first interface to press against and become in pressurized contact with a ground planar surface of the receiving structure. A second annular volume is pressurized to urge the second interface to press against and become in pressurized contact with a signal planar contact of the receiving structure. The pressurized contact of the first interface and the ground plane surface is independent of the pressurized contact of the second interface and the signal planar contact.
In an alternative embodiment of the pneumatic planar probe, the first probe body is made into two independently slidable members that are electrically and mechanically interfaced by means of a plurality of contact fingers. The pneumatic planar probe is held in a header by means of a retaining ring. The header, the pneumatic planar probe and the retaining ring are designed to facilitate both the insertion of the pneumatic planar probe into the header and removal of the pneumatic planar probe from the header.